The present invention relates to a process and to an apparatus for producing stacks of printed products provided with an additional sheet. A process and an apparatus of this general type are known, for example, from CH-A-667 065 and the corresponding U.S. Pat. No. 4,565,130.
In the prior apparatus, a compartment is located beneath a preliminary stacking compartment, in which the printed products, which are fed from above, are stacked to form preliminary stacks. The preliminary stacks, after having been rotated through 180° in each case, are discharged in a state in which they have been rotated in relation to one another. The cover sheets, which are prepared in an arrangement for supplying loose and printed cover sheets, are introduced into the compartment by means of a cover-sheet conveyor, with the result that in each case one printed cover sheet ends up located on the complete stack or beneath the stack which is to be built up in the compartment.
EP-A-0 968 947 and the corresponding U.S. Pat. No. 6,241,233 disclose an arrangement in which, at the same time as a complete stack is ejected out of the compartment, a cover sheet on which the next stack ends up located is drawn into the compartment.
In the case of a process which is known from EP-A0 894 721, and of a corresponding arrangement, the complete stack, comprising sub-stacks which are set down one upon the other in a state in which they have been rotated through 180°, is ejected out of the compartment in each case with the aid of a slide and fed to a printer and delivery means, with the aid of which the stack is provided with a cover sheet. Once again with the aid of a slide, the stack provided with a cover sheet is conveyed into a strapping position and strapped.
A further process and a further arrangement for the protective wrapping of stacks of printed products are known from WO-A-00/34127. Stacks of printed products which each have an edge distinguished by an increased thickness are wrapped such that those stack sides in which the distinguished edges are arranged are completely covered by the wrapper and thus protected to good effect. Since the above mentioned stacks are not particularly stable in a direction transverse to the distinguished edges, the stacks are ejected, parallel to the distinguished edges, out of a stacking compartment, in which they are formed, directly between the forms of a pair of forks. The stack is pressed between the forks, and the pair of forks, together with the pressed stack, is guided through a curtain of wrapping material. The wrapping material is then closed around the pair of forks and around the stack, and the wrapped stack, once the wrapper has been provided, is separated from the pair of forks, by the latter and the stack moving relative to one another, and conveyed away. A pressing fork may be equipped with a movable compartment for a cover sheet, which is to be supplied in the ejecting position to a stack, or for applying another flat product. In the case of the wrapped stack and pair of forks being separated, the compartment with the pair of forks is drawn out of the wrapper and the cover sheet remains on the stack.
EP-A-0 586 802 and the corresponding U.S. Pat. No. 5,370,382 disclose an arrangement for forming stacks from folded printed products, in which a preliminary stacking compartment is closed at the bottom by means of slide plates and intermediate base elements can be pushed into the stacking compartment above the slide plates, the fed printed products being set down one upon the other on said intermediate base elements at the beginning of a sub-stack forming operation. As soon as a certain number of printed products have been stacked, the intermediate base elements are drawn out of the stacking compartment, as a result of which the stacked printed products drop onto the slide plates and the sub-stack is finished by virtue of further printed products being fed. The finished sub-stack is then set down on a raisable and lowerable compartment base by virtue of the slide plates being moved apart from one another.
According to the known processes, and using the known apparatuses, the recipient specific number of printed products are stacked to form a complete stack and provided with a cover sheet, and then wrapped in sheet material or tied by means of a band. If a number of recipients are to be supplied one after the other with a relatively small number of printed products, the complete stacks with the correspondingly small number of printed products are put together, stacked one upon the other and once again wrapped or bound for transportation and handling purposes. This requires arrangements for storing the complete stacks on an intermediate basis, setting them down one upon the other and wrapping or binding them.
The object of the present invention is thus to improve the known process and the apparatus of the described type such that the additional arrangements mentioned above can be dispensed with.